45.
Organic Matter In Soil
Best Defense Against Erosion And Water Shortages
By Donald P. Hopkins
Organic matter in soil can absorb and store much more water than can inorganic fractions. It acts like a sponge, taking up water and releasing it as required by plants. It also helps bind soil particles into larger aggregates, or crumbs. Soils with this kind of structure are very resistant to erosion. Conversely, nearly all soils containing little or no organic matter are very susceptible to erosion.
Besides absorbing water readily, a good cropland soil should be able to dry out or warm up quickly when the rain is over. It should hold enough moisture to supply the needs of a crop between rains, yet permit water to pass through the soil. A good soil will not stay too wet or too dry.
There are other, less obvious relationships between soil erosion and crop selection and management. Many soils can be planted with maize without much erosion risk if the maize crop is rotated with legumes and small grains. If maize is planted year after year, however, soil losses begin to mount.
Besides absorbing water readily, a good cropland soil should be able to dry out or warm up quickly when the rain is over. It should hold enough moisture to supply the needs of a crop between rains, yet permit water to pass through the soil. A good soil will not stay too wet or too dry.
There are other, less obvious relationships between soil erosion and crop selection and management. Many soils can be planted with maize without much erosion risk if the maize crop is rotated with legumes and small grains. If maize is planted year after year, however, soil losses begin to mount.
"A governmental policy which results in impoverishing the natural fertility of land, no matter by what particular name it is called must have an end. It is only a question of time when this truly spendthrift course, this abuse of the goodness of Providence, shall meet its inevitable punishment.
Down to this day, great cities have ever been the worst desolators of the earth. It is for this that they have been so frequently buried many feet beneath the rubbish of their idols of brick, stone, and mortar, to be exhumed in after ages. . . . Their inhabitants violated the laws of nature which govern the health of man and secure the enduring productiveness of the soil.
